1. Field of the Invention
The present invention relates to a novel heat-developable light-sensitive material containing decolorizable dyes and having excellent decolorizeation performance and storability.
The present invention also relates to a method of forming color images which provides excellent color differentiation and sharpness.
The present invention further relates to a method of forming color images readily and quickly through a heat development process.
2. Description of the Related Art
A silver halide light-sensitive material is characterized by high light sensitivity and by providing high-definition images. However, because of use of processing solutions having a complex composition, a development process for this material involves adverse effect on the environment and complicated solution control. In recent years, there have been developed and sold heat-developable dye-transfer type light-sensitive materials which can readily and quickly form high-quality color images through use of a small amount of water and application of heat without use of development-processing solute well as image-forming apparatuses which make use of such light-sensitive materials (PICTROGRAPHY 2000 and 3000 and PICTROSTAT 100 and 200 manufactured by Fuji Photo Film Co., Ltd.). Also, heat-developable, silver-salt-diffusion-transfer type light-sensitive materials are described in Japanese Patent Application Laid-Open (JP-A) Nos. 62-283332 and 63-198050. However, it has been found that images formed from such diffusion-transferred dyes or silver do not have sufficiently satisfactory sharpness in certain uses such as color negatives and plate-making intermediate materials.
Meanwhile, colloidal silver or filter dyes have been used for the purpose of improving color differentiation and sharpness. However, since colloidal silver forms fog nuclei, it must be isolated from a silver halide emulsion layer, thus incurring an increase in overall layer thickness due to employment of an additional intermediate layer(s). Thus, the effect of use of colloidal silver is greatly reduced. Filter dyes which have conventionally been used are eluted into a processing solution or cause decolorizeation. When such filter dyes are applied to a heat-developable light-sensitive material, they, together with image-forming dyes, are transferred onto a dye-fixing material, or cause image contamination due to insufficient decolorizeation. Further, in a system in which a light-sensitive material is heat-developed with a small amount of water being applied thereto, water-soluble dyes, when used, are eluted into the water and contaminate the water. Accordingly, the water cannot be used repeatedly.
An image-forming method which solves the above problems is disclosed in JP-A No. 6-337511. In this method, water-insoluble organic pigments are dispersed in a light-sensitive material in the form of solid fine grains, and the light-sensitive material is heat-developed in the presence of water. Since no organic pigments are transferred to a dye-fixing material, dye images are not contaminated. However, when certain sharpness is to be achieved as described above, transferred images are not usable, and thus there is no choice but to use images formed on the light-sensitive material. This is not preferred, since water-insoluble organic pigments remain on the light-sensitive material.
To solve the above problem, a method of forming images through use of solid dispersion dyes is disclosed in JP-A No. 8-101487. However, this method has been found to involve the following problems: part of dyes are solubilized and move during storage of a light-sensitive material; and the reactivity between couplers and color developing agents deteriorates.
JP-A No. 9-146247 discloses a system in which substances color-developed by leuco dyes and color developers are decolorized by alkali during a development process. This system exhibits excellent decolorizeation, but requires a large amount of color developers. Thus, this system consumes alkali so that the reactivity between couplers and color developing agents deteriorates.
For simple, quick processing without use of processing solutions or with minimized use of processing solutions, the present inventors studied a method in which an exposed light-sensitive material is used while it is unfixed. As a result, this method has been found to involve the following problems: the color differentiation of green light and red light from blue light is insufficient due to the insufficient difference between the intrinsic sensitivity of silver halide contained in a blue-light-sensitive layer and that of green-light-sensitive and red-light-sensitive layers; sharpness is impaired due to halation during photographing; and image quality is impaired due to optical scattering caused by remaining silver halide. To solve these problems, the present inventors have found a method in which coloring dyes having a certain structure are introduced into a light-sensitive material, and in addition, a silver halide emulsion which contains tabular grains primarily having (100) and (111) major faces with high silver chloride content is used.
A photographic silver halide light-sensitive material must have high sensitivity. Sensitivity is effectively increased by increasing the sensitivity of silver halide grains or the amount of application of silver halide.
As a technique for applying the advantage of quick development of an emulsion with high silver chloride content to a photographic light-sensitive material, a technique for using in a photographic light-sensitive material an emulsion containing tabular grains having (100) major faces with high silver chloride content is disclosed in U.S. Pat. Nos. 5,264,337, 5,292,632, and 5,310,635 and WO 94/22,054. An emulsion with high silver chloride content was used to obtain a high developing speed, and the same processing solutions can be used for processing both photographic light-sensitive materials and printing light-sensitive materials. However, these publications do not mention the incorporation of certain coloring dyes into a light-sensitive material.
Also, according to Japanese Patent Application Publication (JP-B) No. 7-120014, a heat-developable light-sensitive material exhibits high sensitivity and less fogging through use of silver halide grains having (100) major faces and having such an aspect that the length of one side is at least two times or at most 0.5 times an arithmetic mean of lengths of two other sides. However, these methods do not provide improved picture quality, particularly improved sharpness.
Silver chloride tabular grains having (100) major faces are also described in various other publications; for example, U.S. Pat. No. 5,314,798, EP-534,395A, EP-617,321A, EP-617,317A, EP-617,318A, EP-617,325A, Wo 94/22,051, EP-616,255A, U.S. Pat. Nos. 5,356,764, 5,320,938, and 5,275,930.
Tabular grains having (111) major faces are described in various publications, for example, U.S. Pat. No. 4,439,520. U.S. Pat. No. 5,250,403 describes very thin tabular grains having an average equivalent circular diameter of at least 0.7 Mm and a thickness of not greater than 0.07 Mm. Further, U.S. Pat. No. 4,435,501 discloses a technique for epitaxially growing a silver salt on the surfaces of tabular grains. Also, techniques for the improvement of performance of tabular grains are disclosed in EP-0,699,947A, EP-0,699,951A, EP-0,699,945A, EP-0,701,164A, EP-0,699,944A, EP-0,701,165A, EP-0,699,948A, EP-0,699,946A, EP-0,699,949A, and EP-0,699,950A. These publications disclose techniques regarding silver bromide and silver iodobromide, but do not mention silver halide grains of silver chloride having (111) major faces. Also, no mention was made of actions and effects of coloring dyes having a certain structure in the case where these coloring dyes are used in light-sensitive materials.
Meanwhile, it is observed that for a light-sensitive material containing processing agents, coloring dyes, if contained, prolong the development time. This is because the coloring dyes consume alkali for their dissociation. Accordingly, it has been difficult in some cases to incorporate a sufficient amount of coloring dyes into a light-sensitive material.